user/sven/linux.git/lib/percpu_counter.c, branch v2.6.32.40

percpu: fix list_head init bug in __percpu_counter_init()

2010-12-09T21:26:37Z

commit 8474b591faf3bb0a1e08a60d21d6baac498f15e4 upstream. WARNING: at lib/list_debug.c:26 __list_add+0x3f/0x81() Hardware name: Express5800/B120a [N8400-085] list_add corruption. next->prev should be prev (ffffffff81a7ea00), but was dead000000200200. (next=ffff88080b872d58). Modules linked in: aoe ipt_MASQUERADE iptable_nat nf_nat autofs4 sunrpc bridge 8021q garp stp llc ipv6 cpufreq_ondemand acpi_cpufreq freq_table dm_round_robin dm_multipath kvm_intel kvm uinput lpfc scsi_transport_fc igb ioatdma scsi_tgt i2c_i801 i2c_core dca iTCO_wdt iTCO_vendor_support pcspkr shpchp megaraid_sas [last unloaded: aoe] Pid: 54, comm: events/3 Tainted: G W 2.6.34-vanilla1 #1 Call Trace: [] warn_slowpath_common+0x7c/0x94 [] warn_slowpath_fmt+0x41/0x43 [] __list_add+0x3f/0x81 [] __percpu_counter_init+0x59/0x6b [] bdi_init+0x118/0x17e [] blk_alloc_queue_node+0x79/0x143 [] blk_alloc_queue+0x11/0x13 [] aoeblk_gdalloc+0x8e/0x1c9 [aoe] [] aoecmd_sleepwork+0x25/0xa8 [aoe] [] worker_thread+0x1a9/0x237 [] ? aoecmd_sleepwork+0x0/0xa8 [aoe] [] ? autoremove_wake_function+0x0/0x39 [] ? worker_thread+0x0/0x237 [] kthread+0x7f/0x87 [] kernel_thread_helper+0x4/0x10 [] ? kthread+0x0/0x87 [] ? kernel_thread_helper+0x0/0x10 It's because there is no initialization code for a list_head contained in the struct backing_dev_info under CONFIG_HOTPLUG_CPU, and the bug comes up when block device drivers calling blk_alloc_queue() are used. In case of me, I got them by using aoe. Signed-off-by: Masanori Itoh Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-01-07T01:10:04Z

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: fix rcutorture bug rcu: eliminate synchronize_rcu_xxx macro rcu: make treercu safe for suspend and resume rcu: fix rcutree grace-period-latency bug on small systems futex: catch certain assymetric (get|put)_futex_key calls futex: make futex_(get|put)_key() calls symmetric locking, percpu counters: introduce separate lock classes swiotlb: clean up EXPORT_SYMBOL usage swiotlb: remove unnecessary declaration swiotlb: replace architecture-specific swiotlb.h with linux/swiotlb.h swiotlb: add support for systems with highmem swiotlb: store phys address in io_tlb_orig_addr array swiotlb: add hwdev to swiotlb_phys_to_bus() / swiotlb_sg_to_bus()

percpu_counter: FBC_BATCH should be a variable

2009-01-06T23:59:13Z

For NR_CPUS >= 16 values, FBC_BATCH is 2*NR_CPUS Considering more and more distros are using high NR_CPUS values, it makes sense to use a more sensible value for FBC_BATCH, and get rid of NR_CPUS. A sensible value is 2*num_online_cpus(), with a minimum value of 32 (This minimum value helps branch prediction in __percpu_counter_add()) We already have a hotcpu notifier, so we can adjust FBC_BATCH dynamically. We rename FBC_BATCH to percpu_counter_batch since its not a constant anymore. Signed-off-by: Eric Dumazet Acked-by: David S. Miller Acked-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branches 'core/futexes', 'core/locking', 'core/rcu' and 'linus' into core/urgent

2009-01-06T08:32:11Z

locking, percpu counters: introduce separate lock classes

2008-12-29T12:43:00Z

Impact: fix lockdep false positives Classify percpu_counter instances similar to regular lock objects -- that is, per instantiation site. The networking code has increased its use of percpu_counters, which leads to false positives if they are treated as a single class. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar

revert "percpu_counter: new function percpu_counter_sum_and_set"

2008-12-10T16:01:52Z

Revert commit e8ced39d5e8911c662d4d69a342b9d053eaaac4e Author: Mingming Cao Date: Fri Jul 11 19:27:31 2008 -0400 percpu_counter: new function percpu_counter_sum_and_set As described in revert "percpu counter: clean up percpu_counter_sum_and_set()" the new percpu_counter_sum_and_set() is racy against updates to the cpu-local accumulators on other CPUs. Revert that change. This means that ext4 will be slow again. But correct. Reported-by: Eric Dumazet Cc: "David S. Miller" Cc: Peter Zijlstra Cc: Mingming Cao Cc: Cc: [2.6.27.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

revert "percpu counter: clean up percpu_counter_sum_and_set()"

2008-12-10T16:01:52Z

Revert commit 1f7c14c62ce63805f9574664a6c6de3633d4a354 Author: Mingming Cao Date: Thu Oct 9 12:50:59 2008 -0400 percpu counter: clean up percpu_counter_sum_and_set() Before this patch we had the following: percpu_counter_sum(): return the percpu_counter's value percpu_counter_sum_and_set(): return the percpu_counter's value, copying that value into the central value and zeroing the per-cpu counters before returning. After this patch, percpu_counter_sum_and_set() has gone, and percpu_counter_sum() gets the old percpu_counter_sum_and_set() functionality. Problem is, as Eric points out, the old percpu_counter_sum_and_set() functionality was racy and wrong. It zeroes out counters on "other" cpus, without holding any locks which will prevent races agaist updates from those other CPUS. This patch reverts 1f7c14c62ce63805f9574664a6c6de3633d4a354. This means that percpu_counter_sum_and_set() still has the race, but percpu_counter_sum() does not. Note that this is not a simple revert - ext4 has since started using percpu_counter_sum() for its dirty_blocks counter as well. Note that this revert patch changes percpu_counter_sum() semantics. Before the patch, a call to percpu_counter_sum() will bring the counter's central counter mostly up-to-date, so a following percpu_counter_read() will return a close value. After this patch, a call to percpu_counter_sum() will leave the counter's central accumulator unaltered, so a subsequent call to percpu_counter_read() can now return a significantly inaccurate result. If there is any code in the tree which was introduced after e8ced39d5e8911c662d4d69a342b9d053eaaac4e was merged, and which depends upon the new percpu_counter_sum() semantics, that code will break. Reported-by: Eric Dumazet Cc: "David S. Miller" Cc: Peter Zijlstra Cc: Mingming Cao Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

percpu_counter: fix CPU unplug race in percpu_counter_destroy()

2008-12-10T16:01:52Z

We should first delete the counter from percpu_counters list before freeing memory, or a percpu_counter_hotcpu_callback() could dereference a NULL pointer. Signed-off-by: Eric Dumazet Acked-by: David S. Miller Cc: Peter Zijlstra Cc: Mingming Cao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

percpu counter: clean up percpu_counter_sum_and_set()

2008-10-09T16:50:59Z

percpu_counter_sum_and_set() and percpu_counter_sum() is the same except the former updates the global counter after accounting. Since we are taking the fbc->lock to calculate the precise value of the counter in percpu_counter_sum() anyway, it should simply set fbc->count too, as the percpu_counter_sum_and_set() does. This patch merges these two interfaces into one. Signed-off-by: Mingming Cao Acked-by: Peter Zijlstra Cc: Signed-off-by: Andrew Morton Signed-off-by: "Theodore Ts'o"

percpu_counter: new function percpu_counter_sum_and_set

2008-07-11T23:27:31Z

Delayed allocation need to check free blocks at every write time. percpu_counter_read_positive() is not quit accurate. delayed allocation need a more accurate accounting, but using percpu_counter_sum_positive() is frequently is quite expensive. This patch added a new function to update center counter when sum per-cpu counter, to increase the accurate rate for next percpu_counter_read() and require less calling expensive percpu_counter_sum(). Signed-off-by: Mingming Cao Signed-off-by: "Theodore Ts'o"